#include <stdio.h>
#include <math.h> 
int main()
{
    float a,b,c,s,area;

	scanf("%f%f%f",&a,&b,&c);
	s = (a+b+c) /2.0;
	area = s*(s-a)*(s-b)*(s-c);
	
	if(area < 0)
	{
		printf("false");
	}
	else
	{
		area = sqrt(area);
		printf("The area is: %f",area);
	}
    return 0;
}
